Early Electric Pick-ups for 78 rpm Records.
Some of the items described below (and all four of the above pickups) came from the collection of the late Ron Armstrong, which covered all aspects of early sound reproduction. I never knew him, but dedicate this web-page to his memory.
Electric recording on disc, as we all know, became truly practical when Western Electric in the U.S.A. threw a lot of money at the question, in the early 1920s, in order to make still more of it. Of course, there had been earlier pioneers of electrical recordings; after all, there is hardly anything new under the sun. Thanks to Christer Hamp’s excellent website, you can see details of patents on electric recording which go back to 1888! (See Appendix 1)
But Western Electric, with their corporate resources, made it work very well indeed. It was introduced, quite subtly, by the major labels Victor & Columbia, in 1925. Subtly of course, because they didn’t want to make their existing catalogues obsolete overnight; they needed time to gradually remake all their best-selling mechanical recordings by the new system.
Clearly, electrical reproduction was the next most obvious thing to go for.
Some epoch-making inventions seem absurdly simple and obvious to us today. Edison’s 1877 tinfoil phonograph is one such – it is extremely primitive. It often seems a wonder that nobody did something similar, decades or even centuries earlier. Sound consists of vibrations that pass through the air, and this had been known since the days of Aristotle (384 – 322 BC). But it seems that few if any tried to ‘write down’ sound before Léon Scott de Martinville succeeded in the late 1850s. Even then, no attempt was made to play it back, though he knew that this was a possibility. Being cynical, one might comment that had one been able to kill people with sound recording, or at very least to make a lot of money from it, it would have appeared much earlier…
Ironically, the year before Edison stumbled over the tinfoil acoustic phonograph (for it came, even to him, serendipitously), Alexander Graham Bell had made the first practical electric telephone. It worked by the simple but elegant natural law that magnetism and electricity are, as it were, interchangeable. In 1820, the Danish scientist Oersted had observed that an electric current flowing through a wire deflected the needle of a nearby magnetic compass. It was soon discovered that the converse is also the case: a magnet moved towards (or away from) a wire, induces an electric current in it. This page is not a history of 19th electrical investigations, fascinating though they are; but we have covered these core principles because most early electrical gramophone pick-ups employed coils of wire and magnets, in much the same way as Bell’s telephone. Here is a crude diagram of a typical early pick-up:
We have a magnet, typically the classic horse-shoe shape. The North & South poles are, of course, at the ends of the arms. It doesn’t matter which way round they are; the main things are the magnetic field is concentrated at the poles, and opposite poles attract each other. In order to intensify the magnetic field, two pole pieces (only one is arrowed) serve to bring the magnetic field (the green arrows) as close together as possible, but still leaving a gap. Now, the field in the gap is as strong as can be. There are two things in this gap. First, a coil of wire. It’s flat – the edge is facing you in the sketch. The coil has a hole in the middle of it, and the second thing – in red – the iron armature, goes up through this hole, where it is shown dotted. The armature is pivoted at the, er.. pivot 8^) , and the needle, or stylus if you prefer, is rigidly attached to the armature. Thus, when the groove of the disc goes past the needle, the needle moves from Left to Right &c., as the sound engraved in the groove dictates. This means that the armature moves in exact sympathy with the groove, albeit in the opposite direction, but that’s not important. What is important, is that the top of the iron armature, moving in the strong magnetic field in the tiny gap, disturbs the magnetic field between the pole pieces. And, since we have a coil of wire positioned in a changing magnetic field, Lo! an electric current is induced in the wire, varying in the same way as the sound in the groove of the record. Q.E.D.: All we need to do is to connect the ends of our coil to an amplifier, and bingo – we can hear our record reproduced electrically instead of mechanically. Whoopee! It was simple after all, wasn’t it? We’re sure that Oersted would have been really pleased, could he have known that this sort of thing was going to happen – I would think; wouldn’t you? 8^)
Naturally, in practice, many different configurations were used. Bar magnets were arranged in a square; the linkage from the needle to the armature took many forms; the suspension of the armature and the crucial ‘damping’ to avoid resonance (See Appendix 2) all provided features that could be patented – and usually were! The great majority of pick-ups between 1927 and the advent of the piezo-electric pick-up in the later 1930s worked on the principle described above.
We’ll now start to examine some actual vintage electric pick-ups & arms in detail. In order to present them in a logical order, I have arbitrarily created three ‘classes’. Class 1 comprises electric pick-ups which were mounted on the existing tone arm of an acoustic gramophone. This is subdivided into Class 1a and Class 1b. In Class 1a the electrical connections are made to pillar terminals located on the pick-up itself. Class 1b pickups are equipped with a flying lead. Generally speaking, Class 1b is later than 1a. Class 2 pickups are mounted on a dedicated arm (usually as an integral part of it) which was intended to replace the entire tone arm of the gramophone. From time to time, one sees gramophones with two arms – the original mechanical tone arm as well as an ‘add-on’ electric one. This makes perfect sense; if the machine was a portable, you could still play it out of doors without electricity. And if the machine was a cabinet type, you could still play records if there was a power cut, a common occurrence in those days.
Class 1a pick-ups.
In early 1927, a patent specification was drawn up in London for one of the first electrical pick-ups, developed by J. B. Woodroffe, and sold by the firm of J. Glasscoe & Co. It was a most successful design, and by September that year, had been adopted by the BBC, for in order to broadcast records, the BBC had hitherto had to place a microphone near the horn of an acoustic machine. The Woodroffe was naturally well reviewed in ‘The Gramophone’, but they were very expensive at £3 15s – far more than a week’s wages for most people, so they are not often found today.
A YouTube video describing & demonstrating the Woodroffe in action may be seen at: http://youtu.be/j8ZhZE4o4eQ
Above left is a typical, budget-price acoustic spring-driven gramophone, probably circa 1925. One simply removed the sound-box and replaced it with the electric pick-up, as shown at right. A pair of wires, typically standard twisted ‘flex’, was connected to the two nickel-plated pillar terminals: coaxial cable was a rarity at the time. The signal was fed into your radio set (See Appendix 3). Several different sizes of tone arm were in use, so an adaptor bush was often needed; alternatively, as you will see below, the socket on the pickup was often made adjustable. Incidentally, we should mention that the Woodroffe’s main mounting bush is made of aluminium, which is non-magnetic – this helps isolate the horse-shoe magnet from the steel tone arm, which otherwise might drain away some of the magnetism. Very careful design!
Here are 6 more Class 1a pick-ups. 1: A brightly chromium plated BTH, with a ‘castellated’ mounting socket. 2: A Lissen with an aluminium case. 3: The S.G. Brown GPU No.2. 4: The Burndept. 5: An incomplete pick-up; alas, the front is missing and would doubtless have given the manufacturer’s name. 6. The ‘Ajax’ four-pole pick-up. All of these are still in working order except, obviously, No.5.
1. This BTH (British Thompson-Houston) is a classic single coil design which was repeated for years by many different makers, possibly under licence. The armature A – the moving element oscillated by the needle in the groove – is pivoted between the pole pieces P by two small rubber tube suspensions, which have disintegrated in this item as usual after ~ 80 years. The rest of the armature passes up through the coil C, and then goes between the tiny gap in the upper parts of the pole pieces. It is at this point that the lateral movement of the armature induces a current into the coil. Finally, the top of the armature, which is flattened and often called the ‘fish-tail’, passes into D, a rubber block which both supports it vertically and damps out any mechanical resonance. (See Appendix 2 for more on resonance). The rear of the pick-up has the pillar terminals for the connecting wire, and helpfully tells us that the patent for this item was applied for in 1929. BTH continued to make this pick-up for some years. It is actually found more frequently ‘all of a piece’ with its BTH pick-up arm, illustrated below under Class 2. The DC resistance of the coil in this example is only 880 ohms, and the pickup weighs just over 200 g. We are told by G. A. Briggs that a few BTH ‘needle armature’ pickups were still in use by the B.B.C. as late as 1949, albeit a lighter version than this one, introduced in 1933. (G. A. Briggs, ‘Sound Reproduction’. Wharfedale Wireless Works, Bradford, 1949. P.122.)
2. Lissen were a very active company in radio in the 1920s, marketing complete radios as well as components. They were bought out by Ever-Ready in 1929, but continued with their own marque. Their pick-up design is very commendable. At D1 is an adjustable suspension. The armature is large and flat, and passes close to the pole pieces of two coils. It is secured and damped at D2, and this damping is actually externally adjustable by means of the little knob on the outside of the case. Excellent stuff. The case is aluminium so as not to draw any energy from the horse-shoe magnet, and also to save weight. The DC resistance is 2,100 ohms and the weight only 133 grams. Note that unlike the BTH and Woodroffe, which work radially, this device is mounted tangentially, like a normal acoustic sound box. The date must be the late 1920s.
3. Sidney George Brown (1873 - 1948) founded his company in 1903. It made scientific apparatus and was involved in radio from the start. S.G. Brown products were of great repute. This pick-up is for tangential mounting and is simple and elegant. The armature is mechanically pivoted under the bottom of the die-cast case, exactly like an acoustic sound box. At the top it is damped by rubber. There must be a gap between the pole pieces, behind the tapering portion of the armature. It was early in the field, as it was reviewed in the September 1927 ‘Gramophone’ magazine, along with the Woodroffe and the Igranic. The reviewer was slightly critical of the amount of ‘needle talk’ it produced, which he thought implied that record wear might be severe. Unfortunately, we have no price for it. The DC resistance of the coil is 1900 ohms, and its weight a fairly modest 141 grams.
4. Burndept was another long-lived radio company. This device, which works tangentially, is described on the front as ‘Electric Sound Box’ – evidently the old term persisted for some time. The suspension and the damping appear to be combined (always a good idea if possible) at the bottom of the armature, while the fish-tail moves between the pole pieces at the top of the coil; one is at the front left of the coil, the other at the right back. Exploring the design further would require dismantling the item, and now we are of mature years, we hold fast to the tenet: ‘If it isn’t bust, don’t fix it!’ Especially striking is the huge coil, so large that the front of the Bakelite case is shaped to accommodate it. Clearly the coil is wound with the usual very thin, almost hair-fine wire, for its DC resistance is a whopping 5700 ohms! The assembly is steadied inside the case by the strips of orange rubber. It weighs 156 grams. We have no definite date for this device, but probably circa 1930?
5. This unknown is clearly very small: less than 1.5" wide. But the front is missing and the coil is open circuit. The metal ring is actually the end of a tube about 1.25" long, which therefore sticks out of the back of the device, and was used for tangential mounting. The disc, I suspect, is a metal rod concentric with the tube, and fixed into the closed end of it. Therefore the poles of the magnet are the end of the tube and the end of the rod, with the coil filling in the gap between them? The armature is pivoted mechanically, like a sound box, and is damped right above the pivot by the pale orange rubber discs. The pressure on these can be varied by screws which come in from the sides. The top of the armature is simply a small flat disc. The disc is some distance from the end of the rod behind it, so something must be missing. The black housing appears to be ebonite. Any information would be welcomed, please! In its present state it weighs only 80 grams, which is practically nothing by the standards of the time – but when that time was, we have no idea…
A YouTube video of a partially successful restoration of the above pick-up is at
6. The ‘Ajax’ surprises us by having no less than four coils. It’s a fascinating little thing. The armature is pivoted at the top, unlike most. The damping is the little tube just above the needle-grip. Two small headphone-like U-shaped magnets bear four coils, in a structure made of ‘jazzy’ black and brown Bakelite. Unfortunately, it is in very bad shape, the Bakelite on the left having cracked. At the extreme left is a vulcanised rubber tapered sleeve for mounting the device radially. This can be slid off, revealing a smaller mounting tube. The front and back plates are of ‘oxidised’ metal, black but coppery round the edges. They are help in place by four 8BA bolts & nuts, which pass through just inside the four corners of the case. In spite of its current dilapidation, it still works, and thus is crying out to be conserved. Wires connect to pillar terminals on top. The DC resistance is exactly 2000 ohms, and the weight a modest 92 grams. Though the box justifiably proclaims ‘British is Best’, it is reticent regarding the name of the company responsible for this very interesting product which cost 15/- (75p). Date? H’mm; early 1930s?
Class 1b pick-ups.
1. By contrast to Class 1a with their screw terminals, our 1b type have flying leads, and tend to be rather later in date. Above you see the bakelite-cased ‘AED’ pickup in place on an acoustic gramophone. The flying lead went to whatever you were using to amplify the signal (See Appendix 1). This pickup was made by the AED company, probably around 1930 or a bit later. I’d hazard that the letters stand for ‘Acoustic and Electric(al) Developments’ or something similar. The internal assembly is shown at the right, above. This is a horse-shoe magnet with a single coil. AED seems to have been a Limited Company belonging to an inventor & electronic developer called Bowyer-Lowe. (More on this name in Class 2 below.) Note the interesting Trade Mark stamped on the magnet; what is it? A fish?
2. Little could be found on line about the next one shown above, which was made by a company called HEGRA. This might be because HEGRA, nowadays, is an acronym for High Energy Gamma Ray Astronomy, which – however intriguing the subject may now be – simply did not exist when the pick-up was made, probably around 1930. (Besides which there is a Hegra hotel in Amsterdam, and also a place in Norway called Hegra!) This has a bright nickel plated case and a very good wire to connect the output to an amplifier, which remains very flexible even 80 years since it was probably made. Doubtless it is what was called in English ‘tinsel wire’, which consists of a number of very fine copper or copper alloy ribbons which share the current. They are interwoven with cotton threads, which give flexibility and little risk of breakage. Even if one tiny ribbon somehow breaks, there are all the others still intact. Its internal structure is shown at the right. This HEGRA, too, has only one coil. One reason for these rather later pick-ups only having one coil might be that gradually, better magnetic materials were being developed for use in the horse-shoe, which provided the main magnetic field in these devices? It was certainly easier to manufacture such a single-coil pick-up.
3 and 4. Inevitably, the same design appeared under different names, or even as in this case, anonymously. Who made these we do not know, but the second (nameless) pick-up is identical to the ‘Radio Gram’. The fixing sleeve, which is simply fastened to the bakelite body by an eyelet, is of generous diameter, so it would have fitted most acoustic gramophone arms. The internal structure is quite simple, but featuring ‘tapering pole pieces’ (more on this far below). What is interesting about this one is the damping of the armature. In the fourth picture, you see screws which have two wire springs between them. These must be the pivot of the armature. We need both a pivot and also some damping to avoid resonance (See Appendix 2). In this design, the damping must be the sort of rubbery disc around the needle hole, indicated by the yellow arrow, and which locates in a hole in the bottom of the casing. If this is so, then it is the only example I have so far seen where the damping is below the pivot. This would probably have been the principal subject of the patents for which the makers had applied. (‘Pats. Pen.’ = Patents Pending.)
5 and 6. More of the same! But which one is the clone? Don’t know, but will plump for the ‘Royal’, on the basis that Petmecky is – or was – a better-known name. Petmecky gramophone needles were widely advertised and much recommended in the 1920s in the U.K., though they were made by the Petmecky Company of Kansas City, MO, U.S.A. It might even be that the company made these early pickups & exported them, though it says ‘British’ on the case. Whatever, it’s an earlyish example of ‘badge engineering’. But what are they like inside?
Well, pretty conventional. The Petmecky is on the left & has a coil on a lovely clear celluloid former, having a DC resistance of 1,966 Ohms. The Royal has suffered in the past – its horse-shoe magnet has disappeared, and the rest is in bits, though this enables us see the armature D, which is quite short, and has a bit of rubber on the ‘fishtail’ which acts as damping so that it won’t rattle about between the tapered pole pieces. In spite of the fact that the coil has been loose in the case for an unknown number of years – up to 70 or so? – it is still OK and has a DC resistance of 1,538 Ohms. Probably these date from the early 1930s.
7. This ‘Phonovox’ made by the important Igranic Company dates from 1927. We know this because the Gramophone Magazine reviewed three of the first electric pick-ups in September of that year, and this was one of them. (The others were the Woodroffe and the S.G. Brown, both also dealt with on this page.) The pole pieces are brought back upwards to meet at the top of the very large coil, so the length of the armature (L) is quite considerable – probably nearly 1" (25mm). The DC resistance of the coil is about 1,800 Ohms.
8. Millgate, alas, means nothing to us. However, while we were undoing the two screws on the back, which we assumed would release the front casing, we experienced a strange sense of misgiving. You will, of course, have experienced this feeling yourself, if you are in the habit of dismantling ‘old things’ just to see what is inside them. Yes; instead of gradually becoming looser, the first screw became loose almost at once, but then no looser. Frowning, we cautiously tried the second screw, which behaved in exactly the same way. We were now alarmed, because we know that in Olden Times, people possessed the amazing ability (happily, long since lost) to assemble things as it were, from the inside. Which meant that if you unscrewed something, a nut would drop off inside, and then you would never, ever, be able to open the thing to put it back on. To digress, I was once told a specific instance of this. Long ago, a certain British car, had a transverse chassis member. It began as a channel section with end-pieces welded on, and was screwed to the outer frames by big nuts and bolts, done up very tightly indeed. Then, to strengthen the member, a strip was welded along it, turning the channel into a box-section. Therefore, if you were ever to loosen the head of the bolt, the nut inside would come loose and you would never, ever, be able to tighten it up again. Unless you sawed through, or drilled a very large hole in the box section to get at the nut – in which case the transverse member was very seriously weakened indeed & became, in effect, completely useless. Fearing that we had done a like thing, we pulled tentatively at the Bakelite front, which to our immense relief, came off, revealing the inside, and especially the two nuts securing the brass (non-magnetic) strips that hold the pole pieces in place. It was these we had loosened. They were re-tightened, and we breathed a sigh of relief. But what was it that held the front casing on? The surprising answer was – nothing. The front casing just pushes on & sits there, with a fairly loose interference fit. To take it off, all you have to do its remove the needle securing screw, and pull it off! The internal structure is unremarkable, except for the armature, which is again very long indeed, extending fully three-quarters of the height of the pick-up. The coil has a DC resistance of 1000 Ohms.
9. DUX. Again, we have not heard of this make. The styling is very much mid-late 1930s, and at first it looks unlike an ‘add-on’ pick up; but the flying lead and the screw ‘S’ indicates that it is – the fixing sleeve is missing, but that’s where it screwed on. Having said that, there is no reason why add-on pick-ups for 78s might not have been made as late as the advent of the LP – namely 1950. Moreover, the wire in the lead (if not a replacement) is definitely plastic covered; and the patent number stamped on the metal foot-plate – 116062 – is in a very continental type face. We suggest that this is a late manifestation of a Class 1a pick-up, and may date to the 1940s or even the early 1950s!
10 and 11. The Harlie pick-up is encountered quite often. It is one of a group of at least four different ‘makes’ – including Ekco and Cosmocord – which are manifestly the same sheep in a different coat. This Amplion is the fourth we have discovered. Who actually made them, we do not know. They are actually commoner as Class 2 devices (i.e. a complete arm) so we have already dealt with the internal structure under that heading – see below. They date from the earlier 1930s but probably remained in production for 10 years or more, so there could be significant internal variations in that time.
12. Last but not Least, even ‘Mighty HMV’ did not scruple to market a Class 1 pick-up. It was called the ‘No. 11’, and came as an outfit, with connecting leads and volume control. Here it is seen in place on an Electrola gramophone, which is simply the German version of an HMV Model 109. The 109 used the HMV No.4 sound box, and was current until mid-1930.
Here is the lid of the box in which it came. One on-line source states that it cost £1 12s 6d and was introduced in 1935 but it surely must have appeared earlier than that? Perhaps £1 12s 6d was the price in 1935?
Here we have the opened box, which would double as an attractive window display.
Above we see the black bakelite pick-up with its (rusty) securing screw. Then the internal structure: the usual horse-shoe magnet, the single coil and the red rubber damping at the top of the armature. This would have been very easy to replace. One assumes that the suspension of the armature was on the axis of the needle screw, and might have been the simple mechanical form. The coil is anchored by a couple of dollops of varnish. (See also the HMV No.15, dealt with in Class 2 below.) On the right is seen, we think, the complete outfit: the pick-up itself; its cable, terminating in a three pin plug; the volume control, which is a simple potentiometer (see Appendix 3); another three pin plug on a much longer cable which led to your radio set. The plugs are not polarised, so will go in either way. This isn’t a problem, as we have here a ‘twin feeder’ with a separate earth in the middle. The letters on the input are: P – E – U. Pick-up, and Earth. Or Pick – Earth – Up, strictly speaking. The letters on the output side are B – E – C; E is clearly Earth, but what B & C are: who knows? Also you got two chromium-plated clips, which would hold the cable to the tone arm.
A video of a No.11 pick-up in use can been seen at:
Class 2 pick-ups.
That is, those which were marketed as an integrated pick-up and arm, mostly from the early 1930s onwards, which you could buy and fasten on to your acoustic gramophone, entirely replacing its acoustic tone arm.
1. The Bowyer-Lowe Mark IV.
This has British patent number 396,875, which dates to the early 1930s. Bowyer-Lowe had a company which made all manner of radio and electrical components. Its location was Letchworth, and was already in existence in 1925 if not earlier. This arm is extremely well made. It rotates on a ball-race, and needs no ‘arm rest’, the front of the rotating bracket serving this purpose. The counterweight at the back is not adjustable, but balances the arm well. Changing the needle – which of course in those days you did after playing every record – was very convenient with this arm. You simply rotated the head 180º anti-clockwise, as seen below.
The internal structure is the now-familiar horse-shoe magnet, with a single coil in which the armature moves. The playing weight was 95 grams, which was comparatively modest in those times.
Also illustrated here is an empty cardboard box which once contained a Bowyer-Lowe “Beta” pick-up, with adaptor. We do not know what this ‘Beta’ pick-up was. It may have been similar to the one above, but with a mounting for an acoustic gramophone? Date unknown, but there is now some sort of tie-up between Bowyer-Lowe and A.E.D. Ltd. of Brighton. (The £1.50 price label is recent!)
2. The Meltrope Electric Pick-up and Arm.
This section is under revision as at December 2015; we recently acquired a
1929 book on sound reproduction written by Percy Wilson, who designed this arm.
We will be re-writing this entry a.s.a.p.
A very important pick-up and arm, designed by the famous Percy Wilson. Wilson’s Meltrope pick-up embodied a still more revolutionary feature – it had no screw to hold its needle in place. Ever since gramophones had come into existence in the 1880s & 1890s, there had always been a screw to hold the needle in place. Evidently, Wilson would have none of this. He may have been trying to reduce the mass of the armature by getting rid of the needle-screw, which for durability, was made of iron & so increased mass? The less the mass of the armature, the higher its resonant frequency would be… and therefore, the easier to damp out & get rid of… Whatever his reasons, Wilson threw out 40 years of tradition and mounted his needles in aluminium collets. You can see in the pictures above, the thing the needle goes into is a metal tube. However, circa 1930, there were quite a variety of ‘gramophone needles’ in current use. Thin ones to play records quietly (they flexed more & transmitted less energy onto the pick-up); medium ones, which were… well, just medium; and loud ones, which were thick & rigid & sent more energy into the pick-up. [Here, an aside: gramophone needles were actually ‘pins’. A ‘needle’ has an eye, through which you thread your cotton, yarn or whatever, right? A gramophone ‘needle’ does not have an eye, and is therefore a pin. Accordingly, through all those years when countless billions of these were made, all the manufacturers duly referred to them, inside the factory, as ‘pins’.] But besides these, were non-metallic needles – which were much favoured by high-class gramophone enthusiasts of the time. These were the ‘fibre needles’, which reduced wear on records because they were softer than metal. There is no space here to go into all that sort of stuff. There is more than enough material in that subject for a Doctoral Thesis – indeed, I wouldn’t be surprised to learn that one or more has actually been written. If not, I commend it to you as a possible subject. The main point is that some (though not all) of these fibre needles were triangular in section. How then, was the Meltrope to cope with this great variety of thin, medium and thick steel needles, plus some triangular ones? The answer was absurdly simple: a range of at least seven collets was provided, as shown above. In order to take this photograph, I simply stood them up in a group, which was quite difficult as they kept falling over & rolling about. But oddly, they have turned out in some sort of order. The three on the left which have the smallest holes, are probably for thin, medium & thick steel needles. The two at back right are obviously for the triangular fibre needles, and the two at front right are probably for round non-ferrous needles – ‘thorn’ needles as they were called. Years ago, I tested thorns from a hawthorn hedge in the garden of my old house, and they worked quite well. In the United States these are referred to, for obvious reasons, as ‘cactus needles’. There is – or used to be – much lore on how to treat & prepare these thorns to render them more durable. At the risk of boring you to distraction, I quote below one recipe from “Gramophones – Acoustic and Radio”, ‘The Official Handbook of “The Gramophone”’, which dates from not before 1932.
A SUGGESTED DOPE FOR FIBRE NEEDLES.
The object of doping fibres is to make the points tougher so that they are less susceptible to breaking down in the heavy passages of a record, and so that the reproduction is cleaner and the volume slightly greater.
Make a saturated solution of Gum Arabic and water and a saturated solution of Potassium Bichromate and water. When the fibres are ready for doping—not before—thoroughly mix two parts of the Gum Arabic solution to one part of the Bichromate solution in a dark room and leave the needles in the mixture, also in the dark, for at least fourteen days. Then remove and wash the fibres lightly in water and wrap in a cotton duster to remove surface moisture. Allow the fibres to dry in the sunshine or any artificial ultra-violet light such as that used by draughtsmen for taking blue-prints, or even one of the domestic "sunshine" appliances now on the market. When the needles are absolutely dry clip and use in the ordinary way. But remember the "don'ts."
Don't mix the two solutions until the fibres are ready for doping.
Don't expose the mixture to light.
Don't dry the needles in front of a fire or in an oven.
The above is obviously commendable, even if it bears a distinct resemblance to mediaeval alchemy: the ritual of which was at least as important – indeed often very much more so – than the actual physical & chemical processes involved. I mean, if your 78 rpm records didn’t sound better after you had prepared your fibres or thorns in this time-consuming manner, then I really don’t know what to say. I am puzzled though, by the phrase: ‘When the fibres are ready for doping—not before—’ How did people know when the time was right? They do not tell us when this is; so it must have been common knowledge circa. 1932, but has since been lost to us. Did gramophiles of the time, lighting their after-breakfast pipe, stroll around the garden contemplating the primroses & hollyhocks, then after studying the sky for some time and possibly noting the propitious flight of certain birds, call back to the house: “Cynthia darling! It’s time to dope the thorns! Be a sweetie and mix up the Gum Arabic and the Potassium Bichromate, won’t you, eh? I’ll be in presently.”?
5. The Harlie Pick-up Arm.
As mentioned above, these sold well. The knurled knob on top of the arm pivot is marked ‘Max – Min’, and the cable is tinsel wire, very flexible. This is a handsome arm with its pleasant contrast of bakelite and chromium plating, and probably dates from the early to mid-1930s. One notable feature of the pick-up (see below) is the stepped laminations. (These are thin sheets of metal stacked & clamped together – magnetism is transmitted better by a layer of thin strips rather than a solid bar.) The brass nuts holding them tight are painted with a brown coating to stop them coming loose. Above the coil you see that each lamination is slightly longer than the one in front of it, and the only the longest one(s) come right up to the armature – you can just see this coming out of the centre of the coil. This is a good design feature, because the magnetic field from the horse-shoe magnet is concentrated just where it is needed – i.e., each side of the armature. We are very much in the Art Deco period at this time, and the bakelite front cover reflects this.
6. The Cosmocord Pick-up Arm.
The Cosmocord company were based in Enfield, Middlesex. The brand name ‘Acos’ was used by this company later on, and ‘Acos’ became ubiquitous in the 1950s, and for several decades after, with their crystal and ceramic pick-up cartridges, their styli and microphones, besides other products. This arm, again from the early 1930s I guess, is of quite light construction, and also embodies a volume control, this time alongside the pivot. As it a one-piece structure, provision has been made for the head to rotate clockwise to allow the easy changing of needles, as seen at the left. This pick-up has two plates, not laminated, which convey the magnetic field to the armature – although they are tapered to meet it, as in the Harlie above. Again, Art Deco Rules, as the bakelite front cover shows! In fact, there is a great similarity between this front and the front of the Harlie. A similarity which is almost disquieting when one comes to think about it. The insides are fairly different though; the damping in the Harlie seems to be applied to the top of the armature, while that of the Cosmocord is centred on the armature pivot. Still, one wonders whether Harlie made pickups for Cosmocord or vice versa!
7. The ‘Daptacon’ Pick-up Arm.
We acquired a ‘Daptacon’ pick-up head from the Ron Armstrong collection; this is illustrated right at the top of this page. At that time, we were not sure how it fitted into ‘the scheme of things’. But it turned out to be the detached head from a complete assembly, so really belongs in our Class 2. As you see, it is of simple structure, and so probably was budget priced. Also, you can only raise the arm to an angle of abut 40 degrees, and the head does not rotate for the fitting of the new needle, which means you have to more or less ‘fiddle’ the needle into the socket – unless you want to kneel down so that you can see what you are doing. The head itself is of all-metal construction, relatively unusual. It has not a horse-shoe magnet; instead, it has three separate bar magnets in an inverted ‘U’ shape. All these things, we feel, tend to indicate a date further into the 1930s than most of the other examples on this page. Let’s guesstimate 1934/6? Also, there is no provision for the lead to pass through the flange of the pivot. A hole would have to be drilled in the motor board, and the lead pass down to the radio chassis or amplifier. This again indicates a later date?
8. The Marconiphone Pick-up Arm.
Well, we have to say, that this picture is just as much about the box as about the arm! Resplendent in its Art Deco design and ‘chemical red’ colour, the box houses an example of what is probably the most ubiquitous pick-up arm of the mid and later 1930s. By this time, the ‘domestic audio’ side of Marconi was of course part of EMI, which principally included HMV and Columbia. This same arm was fitted to many EMI products. Each arm, whether HMV, Columbia or Marconi, would have borne that company’s logo on the top of the head. Unfortunately, that little ‘Marconiphone’ plate is missing from this example; but that’s not a problem really, as it will be fairly easy to acquire all these types in the future. Another thing that is missing is the arm rest. Some of the arms we have dealt with so far were ‘self-supporting’, but the ‘arm rest’ was gradually becoming obligatory. Again, that’s not important right now. Another sign that we are entering a later period, is the frequency response curve printed on the front flap of the box. Frequency response graphs had been around for many years of course, going right back into the acoustic era; but at that time they were intended for the specialist audiophile – or ‘gramophile’ as they were known in those early days. The fact that ‘the man in the street’ might know enough to be impressed by a frequency response curve, represents a significant change in the way equipment was being marketed… click here to see the curve.
First, we see the arm, looking a little floppy & folorn without its arm rest! Next is the underside of the pick-up. The head did not rotate, but the arm lifted up through a large angle so that fitting a new needle was quite easy – you could see what you were doing. Notice the five screw-holes: they are filled with a thick varnish or solution of shellac – much the same thing. This, we suggest, was not to stop the screws working loose by vibration (though it would have served that purpose), but as insulation to prevent dangerous voltages, up to 250 volts, appearing on the pick-up head. Many radio sets of the time had a ‘live chassis’, as it was called. Without going into detail about this, in some cases the mains voltage could appear on outlying accessories such as a gramophone pick-up. All five holes are here filled. This means that this pick-up has never been opened; or if it has been, the holes have been re-filled with insulating sealant. In any event, we undid the central screw, so you can see the ‘innards’ on the right. These are at an angle, but still consist of a horse-shoe magnet and the inevitable coil of fine wire. The red rubber can be seen, where it damps the upper end of the armature, just as in the HMV No.11 pick-up shown earlier. But there is a startling new feature here! There is ANOTHER coil above, held in place by a brass strip. What is this for? Well, I think it is must be a ‘hum-cancelling’ coil. When Class 1 pick-ups were fitted to acoustic gramophones, there was no problem with ‘AC mains hum’ being induced into the pick-up: those early turntables were usually driven by spring motors. But later, when turntables were driven by AC electric motors, there was a distinct possibility that the alternating magnetic field from those motors might reach the pick-up, the action of which, as we have seen, depends on a varying magnetic field. This ‘AC hum’ would combine with the musical signal from our record, and spoil it. So probably, this pick-up has an extra coil, which is there solely to ‘intercept’ this rogue AC hum. Above all, this coil would be wound ‘in the opposite sense’ to the main coil, so that the hum induced in the main coil would be cancelled out when their outputs were combined.
9. The HMV No.15 pick-up.
This pick-up was an integral part of an arm, or an early HMV ‘record deck’. It has been detached, probably to be kept as a spare part. You obviously turned over to change the needle; there are two ball catches on the brass sleeve, and a pin would engage the slot, and limit the travel. Incidentally, one of my great-grandfathers, Charlie Holder, invented the ball-catch. This was in Wolverhampton; the date is uncertain, but it was not after 1906, as he died in that year. His son (my grandfather Arthur Holder) told me that Charlie was working in a factory when he made the invention, and the owners patented it, and in recognition & compensation gave him a rise of a pound a week to pay him for this useful invention, and also any others he might make. That meant he got fifty shillings a week (£2.50) instead of thirty shillings (£1.50), an immense rise! Alas, the patent specification was very poor, and was easily circumvented by other companies. Worse still, the Trade Union in the factory objected to Charlie’s having so much more money when he essentially did the same work as they did. Accordingly, he went back to 30/- a week. Of course, there might have been some mutually-beneficial connivance between ‘union and management’ in the matter! One consequence of the affair I do know about, was that my grandfather Arthur, born 1882, was thereafter implacably opposed to Trade Unions – even though he himself spent his entire working life (1896 – 1957) on the shop floor, and was indeed member of a Union – though reluctantly! Returning to our main topic, as you can see, the internal structure of the pick-up is virtually the same as the Class 1 HMV No.11 unit shown above. Ball park date? Say 1930?
Two YouTube videos of a No.15 being partly restored, and finally working, may be seen at:
There is a website - http://www.christerhamp.se/phono/index.html - which is principally devoted to the electrical reproduction of phonograph cylinders. It is absolutely fascinating, and everyone interested in such things should explore it. The following are some links to that site, concerning early electric reproduction.
1. In 1888, the French telegraph engineer Mecadier described the electrical reproduction of a tinfoil phonograph recording, the earliest sort of reproducing machine to exist. http://www.christerhamp.se/phono/mercadier.html The diagrams are very lucid and totally ‘modern’, and they are THIRTY YEARS earlier than one might expect! <8^)
2. Also in 1888, Charles Adams Randall in the U.K. described an electrical recording and playback system. His devices were patented in July 1888. However, his system was based upon sound waves simply ‘making and breaking’ a pair of electrical contacts, rather than attempting to follow the precise wave-form of speech or music. It is not known whether his devices were actually constructed. Had they been, the sound could only have been a sort of robotic ‘Dalek’ type. For more info., see http://www.christerhamp.se/phono/randall.html
3. Again in France, 1896 saw François Dussaud employing phonograph cylinders played back via a carbon granule pickup, in his work with people hard of hearing. Dussaud even managed to have a volume control, in that the output from a carbon microphone is, to some extent, proportional to the voltage applied to it. He could vary the voltage applied to the pickup, and hence the volume in the earpiece.
APPENDIX 2. RESONANCE & DAMPING
Any mechanical assembly has a resonant frequency. You have probably driven your car over those thickly-painted yellow lines across the road that are intended to make you slow up when approaching a traffic island? They often produce a distinctly unpleasant bumping up and down of your car – and you! Like anything else mechanical, the suspension of your car has a ‘resonant frequency’, and those thick lines are designed to set the suspension into resonance. Each stripe you drive over can add its impulse to the previous one, so that the resonance builds up, and tells you, in no uncertain way, that you really must slow down. For example, it seems that the resonant frequency of my car is about 5 or 6 ‘cycles per second’, or Hertz (Hz). It is a most disagreeable sensation to be vibrated up and down at such a frequency! A car is relatively big and heavy and so has a low resonant frequency. The smaller the mechanical system, the higher it is. So the resonant frequency of a small armature in an electric pick-up would be quite high. Several hundred Hz, possibly 1,000 Hz or so. The trouble is that this frequency is slap bang in the middle of the range where our music is. So our electric pick-up will produce a far higher output around this frequency than any other, because the vibrating armature ‘prefers’ to vibrate at (or even just near to) its resonant frequency, compared to all the others. This results in distortion of the music we want to listen to.
How can we make our electric pick-up ignore this particular frequency, and reproduce all frequencies evenly? Well, we must ‘damp down’ this resonant frequency. Actually, persisting with the motor car analogy, that it exactly what the shock absorbers on your car do. Otherwise, your car could easily begin jumping up and down from time to time in any case – not just when safety-stripes are painted on roads.
Returning to my favourite old pick-up, the Woodroffe, all is obvious. The curly orange thing wrapped round the two slotted brass pillars is a strip of thick rubber. You can see the smaller screw-heads which anchor it to the pillars. What you can’t see (because it’s behind the yellow wires) is another screw which also anchors the top of the armature to the rubber strip. The purpose of this rubber suspension is to encourage the armature to respond equally to all frequencies, by preventing its tendency to resonate at its ‘preferred frequency’. I have looked at one or two other patent specifications for early pick-ups that can be found on line, and it would seem the method of suspension, or damping, is usually their main subject. After all, the basic idea of converting mechanical vibration into a voltage by a moving armature was really very old by the 1920s, so you couldn’t patent that. But you could patent a novel method of damping the armature – and that is what the inventors of subsequent ‘moving iron’ pick-ups usually seem to have done.
APPENDIX 3. AMPLIFIERS & RADIO SETS.
The more I have dabbled in early electric reproduction of gramophone records, the more obvious has become the very intimate connection between the advent of radio broadcasting (officially January 1923 in the UK), and the rather later beginning of electrical playing of disc records. In other words, the radiogram was inevitable. Indeed, the Brunswick ‘Panatrope’, the first commercially available electric record reproducer, incorporated a radio receiver, and so was indeed a radiogram from the very start.
Let us follow an imaginary purchaser of an add-on electric pickup. The proud owner hurries home with his expensive new item (New Technology has always been expensive), and hastens to fit it to his spring-driven gramophone.
Very well. Now that he had his little audio voltage that corresponded to the music on his 78 rpm disc, what did he do with it? Why, he fed it into an amplifier. The output from this amplifier was connected to a loudspeaker, and Lo! the music poured out, refulgently, into our living room. But where did we get an amplifier in the late 1920s & early 1930s? If we were fairly prosperous in those times and had a radio set, then we already had an amplifier. The last valve in our radio set had the purpose of amplifying a small audio frequency voltage. True, that small voltage had been derived from the radio waves that our aerial had picked up; but one small audio frequency voltage is – generally speaking – much like any other small audio frequency voltage. So by the mid 1930s, most radio sets were equipped with ‘pick-up’ input connections on the back, and we plugged our wires into those.
4. An important accessory: The External Volume Control.
We have seen how these early pick-ups were connected to an amplifier, and that a volume control was needed. Even if we were plugging our pick-up into the back of a radio set (which usually – though not invariably – had a conventional volume control) another one might still be necessary because the pick-up could deliver too high a voltage into the audio amplifying stage, causing overload & hence distortion. Later, complete pick-up arms (e.g. the Harlie and Cosmocord, shown above) incorporated volume controls. But if you had bought a simple add-on pick-up for your spring-driven gramophone, you would almost certainly need to purchase a volume control as well. This was simply a potentiometer: that is, a resistance which you could tap up and down in value by rotating a knob, which adjusted an arm (the wiper) which went around the track of the resistance - but a picture is worth a thousand words…
Left. A complete unit mounted in a bakelite housing, which you would (carefully) screw down in a convenient place. The wander plugs on the pick-up lead went into the two holes at the top, and the flying lead seen at top right would go into the radio set. This unit carries no maker’s name. These black knobs with the arrow were extremely traditional in the later 1920s & 1930s. Centre. A smaller, panel-mounting potentiometer, but still with a traditional knob. Right. The underside of the same device, which reveals that it was imported here from the U.S.A. Scratched into the casing lower right is “1/4 MEG” – that is, one quarter of a Megohm, or 250,000 ohms, the total resistance of the track. The devices illustrated here date from the late 1920s to mid-1930s.
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